Bioprocessing with enzymes and lactic acid bacteria for production of new functional faba bean ingredients: Master's thesis

Faba bean (Vicia Faba L.) is a nutritious high protein crop widely cultivated for uses of both food and feed. Its use has limited due to presence of anti-nutritional factors, including phytic acid, bitter taste and poor technological functionality. Phytic acid is the major storage of phosphorus in cereals and legumes lowering the bioavailability of proteins and micronutrients. The aim of this master's thesis was to study the impacts of bioprocessing with enzymes and lactic acid bacteria on both nutritional and textural value of faba bean flour. Food-grade phytase was applied for degradation of phytic acid in faba bean matrix. Fermentation technology with lactic acid bacteria was studied in aim to improve both technological and nutritional quality of faba bean. The specific objective studied with the aim of improving the technological properties of faba bean matrix with in situ exopolysaccharide, dextran production. The final step was to study the functionality of bioprocessed faba bean ingredients in extrusion. Extrusion process is a high-temperature short-time, modern and versatile operation widely used commercially to produce high-value expanded breakfast and snack foods based on cereals. Enzyme treatments were performed with food-grade phytase with three different enzyme activity doses (2, 10 and 20 U) and three treatment times (1, 2 and 4 h). Lactic acid bacteria fermentation was performed with Weissella confusa VTT E-143403, Leuconostoc lactis VTT E-032298 and Lactobacillus plantarum VTT E-78076. Fermentations were carried in small (0.5 kg) and in large (10-15 kg) scale. Extrusion was performed with twin-screw extruder using the bioprocessed faba bean as a raw material. Raw a material was mixed with rice flour (100 %, 50 % and 25 % addition levels of faba bean). Bioprocessing modified the nutritional value and texture of faba bean flour. Phytase treatment reduced phytic acid over 80 % improving also mineral and amino acid profile of faba bean. Faba bean flour was an excellent material for in situ dextran production. With W. confusa, 6.5 % dextran yield was achieved. Fermentation reduced the flatulence causing oligosaccharides and improved the amino acid and mineral composition. Bioprocessed faba bean flour showed moderate improvement on mechanical properties of extrudates. Maillard reactions caused challenge in extrusions with protein-rich material, especially in fermented samples with in situ produced dextran. However, fermentation with L. plantarum gave 55 % increase in crispiness index and reduced hardness 45 % at addition level of 25 %.